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PROGRAM:

NAME

complexity - Measure complexity of C source

SYNOPSIS

complexity [-flags] [-flag [value]] [--option-name[[=| ]value]] [ <file-name> ... ]

The operands that this program operates on may be specified either on the command line or
read from standard input, one per line. In that input, leading and trailing white space
is stripped, blank lines are ignored. Standard input may not be a terminal.

Compute the complexity of source code not just with a path-through-the-code count, but
also amplifying line counts by logic level nesting.

Compute the complexity of code by counting lines of non-comment source and multiplying by
a nested logic weight factor. By default, 1.9.

DESCRIPTION

The weight of each statement is the number of lines the statement uses. This value is
multiplied by the nested logic weighting (1.9 by default) for each layer of logic. For
example, this snippet:

if (foo) {
if (bar) {
bumble; baz;
}
}

will score 11. This score is then scaled to approximate pmccabe results by dividing by 20
and rounding. This scores "1" at the end. pmccabe scores higher on simple procedures and
complexity scores higher with more deeply nested logic.

The scoring can be tweaked by adjusting the --nesting-penalty and --scale-ing factors.
The default values were calibrated by comparing the average results of millions of lines
of code with the results of pmccabe.

For the purposes of this program, a procedure is identified by a name followed by a
parenthesized expression and then an opening curly brace. It ends with a closing curly
brace in column 1.

This program will perform its function for every file named on the command line or every
file named in a list read from stdin. The arguments or input names must be pre-existing
files. The input list may contain comments, which are blank lines or lines beginning with
a '#' character.

OPTIONS

-t minimum, --threshold=minimum
Reporting threshold. This option takes an integer number as its argument. The
default minimum for this option is:
30

Ignore any procedures with a complexity measure below this threshold. By default,
a complexity score of under 30 is not printed. However, if a histogram and
statistics are to be printed, but not individual procedure scores, then the default
is set to zero. Procedures below this limit are not counted in the statistics.

--horrid-threshold=minimum
zero exit threshold. This option takes an integer number as its argument. The
default minimum for this option is:
100

If any procedures score higher than this threshold, then the program will exit non-
zero. (4/COMPLEX_EXIT_HORRID_FUNCTION, if no other problems are encountered.) By
default, this program exits zero unless one function exceeds the horrid score of
100.

-n factor, --nesting-penalty=factor
score multiplier for nested code.

Linguistic constructs weigh more heavily the more deeply nested they are. By
default, each layer penalizes by a factor of 1.9. The option argument is a
floating point number. The penalty may be 1, but not less.

--demi-nesting-penalty=factor
score multiplier for nested expressions.

By default, this value is halfway between 1.0 and the nesting penalty
(specifically, the square root of the nesting penalty). It refers to a
parenthesized sub-expression. e.g.
((a > b) && (c > d))
contains two parenthesized sub-expressions. This would count 3.5 points. On the
other hand, this:
(a > b && c > d)
contains two relation operators and a logical operator at the same level. These
nested counts will be multiplied together and yield 2.5 * 2.5, or 6.25. Don't do
that. It gets even worse if you have logical ands and ors at the same level.

-s factor, --scale=factor
complexity scaling factor. This option takes an integer number as its argument.

By default, the scaling is 20 which divides the raw score by 20. This was
normalized to roughly correspond to the pmccabe scores:

0-9 Easily maintained code.

10-19 Maintained with little trouble.

20-29 Maintained with some effort.

30-39 Difficult to maintain code.

40-49 Hard to maintain code.

50-99 Unmaintainable code.

100-199 Crazy making difficult code.

200+ I only wish I were kidding.
Score | ln-ct | nc-lns| file-name(line): proc-name
4707 3815 2838 lib/vasnprintf.c(1747): VASNPRINTF

-h, --histogram, --no-histogram
Display histogram of complexity numbers. The no-histogram form will disable the
option. This option may not be preset with environment variables or in
initialization (rc) files.

Instead of printing out each function's score, a summary is printed at the end
showing how many functions had particular ranges of scores. Unless --scores is
specifically called out, the scores will not print with this option specified. The
minimum scoring threshold will also be reduced to zero (0), unless --threshold is
specified.

-c, --scores, --no-scores
Display the score for each procedure. The no-scores form will disable the option.
This option may not be preset with environment variables or in initialization (rc)
files.

If you specify --histogram, individual scores will not be displayed, unless this
option is specified.

-I string, --ignore=string
procedure name to be ignored. This option may appear an unlimited number of times.

Some code has macros defined that confuse the lexical analysis. This will cause
them to be ignored. Other ways to cause functions to be ignored are:

Use K&R syntax for a procedure header.

Use a preprocessing macro to assemble the procedure header.

Simplify your code.
Generally speaking, anything you do that alters normal C syntax will confuse the
lexical analysis. If a procedure is not seen, then it will not get counted. If
code within a procedure is incomprehensible, you will likely get inappropriate
results.

-H, --no-header
do not print scoring header. This option may not be preset with environment
variables or in initialization (rc) files.

If a script is going to process the scoring output, parsing is easier without a
header. The histogram output will always have a header.

-u unifdef-opt, --unifdef=unifdef-opt
Run the source(s) through unifdef(1BSD). This option may appear an unlimited
number of times.

Strip out sections of code surrounded by #if/#endif directives. The option
argument is passed as an argument to the unifdef(1BSD) program. For example:
complexity -u-Dsymbol
would cause symbol to be defined and remove sections of code preceded by #ifndef
symbol directives.

Please see the unifdef documentation for more information.

--unif-exe=prog
Specify the unifdef program.

Alternate program to use for unifdef-ing the input.

-i file-name, --input=file-name
file of file list.

Instead of either a command line list of input files or reading them from standard
input, read the list of files from this file.

--trace=file-name
trace output file.

Print intermediate scores to a trace file.

-?, --help
Display usage information and exit.

-!, --more-help
Pass the extended usage information through a pager.

-> [cfgfile], --save-opts [=cfgfile]
Save the option state to cfgfile. The default is the last configuration file
listed in the OPTION PRESETS section, below. The command will exit after updating
the config file.

-< cfgfile, --load-opts=cfgfile, --no-load-opts
Load options from cfgfile. The no-load-opts form will disable the loading of
earlier config/rc/ini files. --no-load-opts is handled early, out of order.

-v [{v|c|n --version [{v|c|n}]}]
Output version of program and exit. The default mode is `v', a simple version.
The `c' mode will print copyright information and `n' will print the full copyright
notice.

OPTION PRESETS

Any option that is not marked as not presettable may be preset by loading values from
configuration ("RC" or ".INI") file(s) and values from environment variables named:
COMPLEXITY_<option-name> or COMPLEXITY
The environmental presets take precedence (are processed later than) the configuration
files. The homerc files are "$@/complex.conf", "$HOME", "$PROJECT_ROOT/complex.conf", and
".". If any of these are directories, then the file .complexityrc is searched for within
those directories.

ENVIRONMENT

See OPTION PRESETS for configuration environment variables.

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